a. Field of Invention
The invention relates generally to manually actuated power sprayers for mounting to containers of liquids to be sprayed, and more particularly to a trigger operated power sprayer having improved container vent and product discharge controls during pump activation.
b. Description of Related Art
Manually actuated power sprayers, which are well known in the art, may include trigger sprayers adapted for manual operation in dispensing of product from a container attached thereto. During operation of the power sprayer, the container to which the manually actuated power sprayer is mounted must be vented to atmosphere to replenish the container interior with air as liquid product is dispensed. If the container is not properly and efficiently vented, the air volume or head space volume within the container which enlarges as the container is emptied of product eventually becomes sub-atmospheric thereby creating unwanted conditions of hydraulic lock and container collapse. Container venting may be carried out in a multitude of ways, utilizing both active and passive valving. While container vent control may be avoided when using, for example, a collapsible bag as the container of product is dispensed, there exist a multitude of containers and products on the market for which collapsible bags are unavailable or economically prohibitive.
For improved operation of the power sprayer for which venting is required, the function of the vent as well as the product discharge controls must be coordinated such that the container is adequately vented while product is being discharged. Container vent and product discharge valving must also be controlled such that during periods of shipping and storage and other periods of non-use, the vent and product discharge ports remain sealed closed to avoid the possibility of leakage. At the same time, the vent and discharge valve controls must be efficient and economical in use during operation of a power sprayer, and must likewise be efficient and economical to fabricate and assemble into the power sprayer unit.
Among conventional trigger sprayers having a container vent control is one with a flexible seal member for covering a vent hole to prevent leakage of product and to permit venting of the container during dispensing. Heretofore, conventional seal designs have been quite complex and have thus required relatively complicated manufacturing and assembly techniques. For example, conventional vent seals disclosed in U.S. Pat. No. 4,230,277, the disclosure of which is incorporated herein by reference, include non-geometric or complex geometric cross-sections, or protrusions or the like integrally molded therewith as in, for example, U.S. Pat. No. 5,603,434, the disclosure of which is also incorporated herein by reference. The fabrication and installation of such complex prior art designs can significantly increase the overall manufacturing and assembly costs of the trigger sprayer. Other effective container vent controls, as disclosed in U.S. Pat. No. 6,554,211, the disclosure of which is incorporated herein by reference, could also be improved upon in operation.
There thus exists room for improvement in the number of parts, the overall costs associated with manufacturing and assembly, as well as the operation of existing manually activated sprayers, whether such sprayers are of the manual pumping type or of the battery activated type, so long as such sprayers require container vent and product discharge controls.
It would therefore be of benefit to provide a manually actuated pump sprayer having in combination improved means for container venting and product discharge control operable in a repeatable and predictable manner over the life of the pump sprayer. There also remains a need for an improved means for container venting and product discharge control, which is robust in design, efficient to operate, simple to assemble and disassemble, and which is economically feasible to manufacture.